U.S. patent number 3,906,895 [Application Number 05/318,612] was granted by the patent office on 1975-09-23 for spray type apparatus for treatment of metal surface.
This patent grant is currently assigned to Nippon Paint Co., Ltd.. Invention is credited to Minoru Makihara, Ikuo Morino.
United States Patent |
3,906,895 |
Morino , et al. |
September 23, 1975 |
Spray type apparatus for treatment of metal surface
Abstract
An improved spray type apparatus for treatment of a metal
surface with an aqueous solution containing a chemical reagent is
disclosed. The apparatus has a spray chamber including a treating
region, where the aqueous solution is sprayed onto the metal
surface, and a rinsing region where rinsing water is sprayed onto
the metal surface which has been previously treated at the treating
region. The improvement includes the rinsing region having one zone
as a last zone and at least one other zone. Conducting means are
provided between the zones and the treating region such that the
water, after rinsing, can flow from the last zone through all the
other zones to the treating region. A supply means for providing
fresh water is provided at the last zone and an evacuating means is
mounted above the treating place so as to eliminate water therefrom
in a vaporized form.
Inventors: |
Morino; Ikuo (Toyonaka,
JA), Makihara; Minoru (Zama, JA) |
Assignee: |
Nippon Paint Co., Ltd. (Osaka,
JA)
|
Family
ID: |
11535399 |
Appl.
No.: |
05/318,612 |
Filed: |
December 26, 1972 |
Foreign Application Priority Data
|
|
|
|
|
Dec 24, 1971 [JA] |
|
|
46-002657 |
|
Current U.S.
Class: |
118/326; 118/314;
134/60 |
Current CPC
Class: |
C23C
22/76 (20130101); C23C 22/00 (20130101); B08B
3/022 (20130101); C23G 3/00 (20130101); B08B
3/08 (20130101); B05B 13/00 (20130101); B08B
3/10 (20130101) |
Current International
Class: |
B05B
13/00 (20060101); C23C 22/76 (20060101); C23C
22/00 (20060101); B08B 3/10 (20060101); C23C
22/73 (20060101); B08B 3/08 (20060101); B08B
3/02 (20060101); C23G 3/00 (20060101); B05b
001/28 () |
Field of
Search: |
;118/73,314,300,326
;134/60,72 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Stein; Mervin
Attorney, Agent or Firm: Wenderoth, Lind & Ponack
Claims
What is claimed is:
1. In a spray type, tunnel type apparatus for treatment of a metal
surface with an aqueous solution containing a chemical reagent
including a spray chamber having a treating region where the
aqueous solution is sprayed onto the metal surface and a rinsing
region where rinsing water is sprayed onto the metal surface
previously treated at the treating region, the improvement which
comprises the rinsing region being comprised of at least two zones
including a last zone; conducting means provided between said zones
and the treating region and the zone adjacent thereto in such
manner that the water, after rinsing, can flow from the last
rinsing zone through all the other zones to the treating region; a
fresh water supply means provided at the last zone; and an
evacuating means provided with a vapor-liquid separator and mounted
in the treating region so as to eliminate water therefrom in a
vaporized form.
2. The improved spray type, tunnel type apparatus as recited in
claim 1, further comprising a plurality of tanks, one tank
communicating with each zone in the rinsing region for
accommodating rinsing water, the rinsing water in each tank being
transferred to the tank in an adjacent zone.
3. A spray type, tunnel type apparatus having a spray chamber
including a treating region for treatment of a metal surface with
an aqueous solution containing a chemical reagent, a rinsing region
for rinsing the metal surface after treatment with water, said
rinsing region comprised of at least two zones, conducting means
provided between at least one of said zones and the treating region
for sending the water, after rinsing, from the zone to the treating
region, and an evacuating means provided with a vapor liquid
separator and mounted in the treating region so that the air in the
treating region is evacuated with evaporated water.
Description
The present invention relates to an improved spray type apparatus
for treatment of a metal surface with an aqueous solution
containing a chemical reagent.
In the industry handling metal substances or materials, various
treatments are made on metal surfaces: e.g. degreasing, phosphate
conversion coating, chromate conversion coating, oxalate conversion
coating, etc. Such treatments are often carried out by the use of a
spray type apparatus, of which a typical example is shown in FIG. 4
of the accompanying drawings. Thus, FIG. 4 is a schematic sectional
view of a conventional spray type apparatus wherein 1 is a metal
substance to be treated, 2 is an overhead-conveyer for transporting
the metal substance and 3 is a spray chamber provided with
fan-attached ducts 4 and 4' respectively at the inlet and the
outlet. The spray chamber 3 is usually divided into several zones
depending on the kind of the treatment. The spray type apparatus as
shown in FIG. 4 is employed for phosphate conversion coating, and
the spray chamber 3 is divided into five zones, i.e. 3A, 3B, 3C, 3D
and 3E, where degreasing, water-rinsing, phosphating, water-rinsing
and acidulating are performed, respectively. Each of the said zones
is provided with a nozzle 4A, 4B, 4C, 4D or 4E for spraying water
or an aqueous solution containing a degreasing agent, a phosphating
agent or an acidulating agent (hereinafter referred to as "chemical
solution") into the spray chamber 3. Tanks 6A to 6E, provided with
pumps 5A to 5E for sending water or the chemical solutions to the
nozzles 4A to 4E, are furnished to the zones 3A to 3E respectively
and serve as reservoirs for water or the chemical solutions sprayed
in the spray chamber 3. Usually, the tanks 6A and 6C are provided
respectively with heaters 7A and 7C.
When the metal substance 1 is treated with an aqueous solution
containing a degreasing agent in the zone 3A and also with an
aqueous solution containing a phosphating agent in the zone 3C,
some portions of these chemical solutions are carried from the
zones 3A and 3C respectively to the adjacent zones 3B and 3D by the
metal substance 1. Thus, the rinsing waters in the zones 3B and 3D
are contaminated with the chemical solutions, which causes the
deterioration of the metal substance 1 in quality. In order to
avoid such deterioration, fresh water is supplied to the tanks 6B
and 6D so as to maintain a high efficiency of water-rinsing. In
this case, some of the rinsing water, resulting from the said
supply of fresh water overflows and is discharged as, waste water.
The waste water contains as a matter of course, the chemicals used
in the zones 3A and 3C, usually acidic or alkaline substances,
metal ions, surface active agents, oils and fats, etc., and the
discharge of such waste water may have a serious influence on the
environment. Because of this it is desirable to eliminate, harmful
components in the waste water. Since, however, an apparatus for
purification is quite expensive, the said elimination is usually
not practised.
The object of this invention is to provide an improved spray type
apparatus which is slightly modified from a conventional one but
can considerably suppress the production of waste water in
quantity. Such object can be attained by mounting an evacuating
means on a spray type apparatus, particularly above a zone where a
metal substance is treated with a chemical solution, so as to
exhaust water in the waste water as vapor. Especially when
water-rinsing is effected by a multistage system and the amount of
fresh water to be supplied is decreased, the evacuation of the
approximately corresponding amount of water to that as supplied is
satisfactorily accomplished with ease.
In the spray type apparatus of this invention, there is provided a
spray chamber having at least one treating region where a metal
substance is treated with a chemical solution and at least one
rinsing region where the metal substance, transported from the
treating region, is rinsed with water. Characteristically, the
apparatus has an evacuating means mounted on the spray chamber,
favorably above the treating region. Further, it is preferred that
the rinsing region is divided into two or more zones so as to
effect water-rinsing by a multi stage system. Fresh water is
supplied to the last zone in the rinsing region, and an excessive
amount of water therefrom overflows to the adjacent zone. Such
overflowing proceeds successively from one zone to another zone in
the rinsing region and ultimately to the treating region, which may
be also divided into two or more zones. Thus, water contaminated
with the chemical solution carried by the metal substance is
discharged from the rinsing region to the treating region, all of
the regions being within the apparatus itself. By the adoption of
such system, the amount of fresh water to be supplied may be
reduced to about 1/20 - 1/10 in the case that the rinsing region is
divided into two zones and about 1/50 - 1/20 in the case that the
rinsing region is divided into threee zones, compared with that
when the rinsing region consists of a single zone.
Since the overflowed water is ultimately lead to the treating
region, the chemical solution therein may be diluted with the
increase of the amount. Because of the evacuation means mounted on
the spray chamber, however, the water is continuously evaporated,
and the dilution of the chemical solution and the increase of the
amount can be suppressed. The treating region is often heated to
around 40.degree. - 70.degree.C for efficiently conducting the
treatment of the metal substance with the chemical solution, and
such heating is apparently advantageous for evaporation of the
water. For instance, 1 kg of air can contain 0.0488 kg of water at
40.degree.C and 0.276 kg of water at 70.degree.C. Thus, the amount
of water coming from the rinsing region to the treating place can
be balanced with the amount of water evaporating from the treating
region by selecting an appropriate evacuating means and/or a
suitable heating means.
The present invention will be hereinafter illustrated in details
making reference to the accompanying drawings wherein:
FIG. 1 is a schematic sectional view of an embodiment of the spray
type apparatus according to the invention;
FIG. 2 is a schematic sectional view of the said embodiment along
the lines II -- II in FIG. 1; and
FIG. 3 is a schematic sectional view of the part of another
embodiment of the spray type apparatus according to the
invention.
FIG. 4 is a schematic sectional view of a conventional spray type
apparatus;
FIG. 5 is a graph illustrating the relationship between the
temperature of evacuated air and the amount of rinsing water which
was evaporated.
FIG. 6 is a graph illustrating the relationship between the
temperature of chemical solution and the temperature of evacuated
air.
In the apparatus as shown in FIGS. 1 and 2, 11 is a metal substance
to be treated, 12 is an overhead conveyer for transporting the
metal substance and 13 is a spray chamber provided with
fan-attached ducts 14 and 14' respectively at the inlet and the
outlet. The overhead conveyer 12 runs through the spray chamber 13,
which is divided into seven zones.
When the apparatus is used for phosphate conversion coating,
degreasing, water-rinsing, phosphating, water-rinsing and
acidulating are effected in the zone 13A, the zones 13B and 13B',
the zone 13C, the zones 13D and 13D' and the zone 13E,
respectively. These zones are respectively provided with the
nozzles 14A, 14B, 14B', 14C, 14D, 14D' and 14E for spraying water
or a chemical solution and pumps 15A, 15B, 15B', 15C, 15D, 15D' and
15E for supplying the water or the chemical solution to the said
nozzles, the said pumps being furnished on the tanks 16A, 16B,
16B', 16C, 16D, 16D' and 16E, which serve for recovering the water
or the chemical solution sprayed in the spray chamber 13. The tanks
16A and 16C are respectively provided with the heaters 17A and 17C,
which are used for heating the chemical solutions in the said
tanks.
18B' and 18D' are pipes to supply fresh water to the tanks 16B' and
16D'. 18B and 18D are pipes to transfer the overflow water from the
tanks 16B' and 16D' to the tanks 16B and 16D, and 18A and 18C are
pipes to transfer the overflow water from the tanks 16B and 16D to
the tanks 16A and 16C. The pipes 18B' and 18D' are provided with
valves 19B' and 19D' and also with bypath pipes 21B' and 21D',
which are furnished with magnetic valves 20B' and 20D',
respectively. The pipes 18A, 18B, 18C and 18D are branched to form
the pipes 22A, 22B, 22C and 22D, which are provided with the
magnetic valves 20A, 20B, 20C and 20D, respectively. The tanks 16A
and 16C are provided respectively with pipes 24A and 24C having
magnetic valves 23A and 23C for controlling the supply of fresh
water thereto. In the tanks 16A and 16C, there are provided liquid
level gauges 25A and 25C which are connected to detectors 26A and
26C, respectively for detecting the liquid level.
When the liquid level falls below a predetermined level and this is
detected by the detector, the magnetic valves 20B', 20D' and/or
23A, 23C are actuated respectively through circuits 27A and 27C so
that fresh water is supplied to the tanks 16B', 16D' and/or 16A,
16C. Usually, it is preferred that the liquid level be raised by
the actuation of the magnetic valves 20B' and 20D' only. When the
liquid level rises up above a predetermined level, the magnetic
valves 20A, 20C and/or 20B, 20D are actuated through circuits 28A
and 28C, and the rinsing water overflowing from the tanks 16B, 16D
and/or 16B', 16D' through the pipes 18A, 18C and/or 18B, 18D is
discharged through the pipes 22A, 22C and/or 22B, 22D. Thus, the
rinsing water contaminated with chemicals is discharged from the
apparatus. In order to avoid this result, the capacities of fans
31A and 31C are designed to be sufficienly large and the amount of
fresh water to be supplied is so well controlled that the liquid
levels in the tanks 16A and 16C do not rise over a predetermined
level. Further, the openings of the valves 19B' and 19D' are,
preferably, appropriately regulated so that the amount of fresh
water supplied in the tanks 16B' and 16D' is maintained at an
amount less than the decreasing amount of the chemical solution in
the tanks 16A and 16C, whereby the liquid level always tends to
decrease.
On the spray chamber 13, there are mounted ducts 30A and 30C,
through which the air in the zones 13A and 13C is evacuated. The
fans 31A and 31C are respectively provided in the ducts 30A and 30C
to eliminated in a vaporized form, an amount of water which
corresponds to the amount of overflow water travelling through the
pipes 18A and 18C into the tanks 16A and 16C. For elimination of
splashed chemical solution, the splasher means 32A and 32C are
usually provided at the entrance of the ducts 30A and 30C. Further,
condensers 35 and 35' are provided in the ducts 30A and 30C to
condense the vaporized water in the evacuated air into reservoirs
36 and 36'. The thus condensed water is quite pure and may be used
as a part of the fresh water supplied into the tanks 16B' and
16D'.
The fan 34, the ducts 33A, 33B, 33B', the fan 34' and the ducts
33C, 33D, 33D' and 33E are not essential in the apparatus of this
invention, but their provision is desirable in order to introduce
fresh air around the conveyor 12 equipped along the upper wall of
the spray chamber 13 so as to diminish the amount of the rinsing
water and the chemical solution which can attach to the conveyor
and which may cause the corrosion of the conveyor 12. The ducts 14
and 14' are also not essential in the apparatus of this invention
but, if desired, may be provided for preventing the liberation of
the splash or drop of the rinsing water and the chemical solution
and also of moist air out of the apparatus.
In an embodiment of the apparatus of the invention as shown in FIG.
2, the entrance of the duct 30A is forked into two branches so that
the air in the spray chamber 13 can be more uniformly
evacuated.
In an embodiment of the apparatus of the invention as shown in FIG.
3, the rinsing water sent from a tank to another tank is not simply
allowed to overflow but is sprayed into the latter tank. Thus, the
rinsing water collected in the tank 16D' is sent through the pump
15D' and the pipe 14D' and a part of the water is sprayed in the
zone 13D'. The other part of the rinsing water is further sent
through the pipe 40D' and the valve 41D' and sprayed through the
pipe 42D' into the zone 13D. Similarly, the rinsing water collected
in the tank 16D is sent through the pump 15D and the pipe 14D and a
part of the same is sprayed in the zone 13D. The other part is
further sent through the pipe 40D to spray into the next zone (not
shown) for water rinsing. When the next zone is not for water
rinsing but for any other treatment, the rinsing water may be
simply allowed to overflow from the tank 16D to the next tank (not
shown). In such case, the pipe 40D can be omitted.
When the evacuation was made in the apparatus of the invention as
shown in FIGS. 1 and 2 while keeping the temperature of the
chemical solution in the tanks 16A and 16C at 40.degree. to
70.degree.C, the graphs as shown in FIGS. 5 and 6 of the
accompanying drawings were obtained respectively on the
relationships between the temperature of evacuated air and the
amount of rinsing water which was evaporated and between the
temperature of chemical solution and the temperature of evacuated
air under the following conditions: atmospheric temperature,
22.degree.C; relative humidity, 72 %; capacity of each of the fans
31A and 31C, 60 m.sup.3 /min for air of 20.degree.C.
In FIG. 5, the solid line and the dotted line represent the
measured value and the calculated value on the humidity chart in
case of the humidity of evacuated air being 100 %. The reason why
the measured value is partly over the calculated value may be that
a portion of the chemical solution sprayed into the spray chamber
13 is accompanied with evacuated air. However, the measured value
is nearly equal to the calculated value.
When the phosphate conversion coating was carried out with the
apparatus of the invention as shown in FIGS. 1 and 2 using an
alkaline degreasing solution and a zinc phosphate solution
respectively in the zones 13A and 13C under the following
conditions, the necessary amount of fresh water to be supplied was
200 to 300 liters per hour in each of the pipes 18B' and 18D'.
Water corresponding in amount to the supplied amount of fresh water
was eliminated in a vaporized form by evacuation, and no amount of
water was not discharged as waste water:
Area of the treated Outer boxes of electric surface (average)
freezer, 100 m.sup.2 /hour Liquid temperature 70.degree.C in the
tank (16A) Liquid temperature 65.degree.C in the tank (16C)
Atmospheric tempera- 20 to 25.degree.C ture Relative humidity 70 to
75 % Water temperature 18.degree.C
______________________________________
When a conventional apparatus as shown in FIG. 4 was employed for
the phosphate conversion coating as above, 2000 to 4000 liters of
fresh water per hour were required to supply into each of the tanks
6B and 6D. This means that the corresponding amount of waste water
contaminated with the chemical as used to the said supplied amount
of fresh water overflowed and was discharged from the
apparatus.
From such comparison, it is obvious that the amount of fresh water
to be supplied is greatly reduced (e.g. about 1/10) and the
discharge of waste water resulting from the supply of fresh water
is avoided by the use of the apparatus of the invention. Further,
it is a great advantage of this invention that the chemical which
contaminates the rinsing water is recovered into the original
chemical solution and can be used again. Thus, the consumption of
the chemical solution is greatly economized, for instance, to an
extent of 10 to 30 %.
In the apparatus of the invention as shown in FIGS. 1 and 2, two
zones are provided for each water rinsing. The number of such zones
may be generally from 2 to 8, preferably from 2 to 5.
Further, the said apparatus has been hereinabove explained in the
case of application to the succeeding performance of degreasing,
water-rinsing, phosphating, water-rinsing and acidulating, but it
may be applied for the performance of a single chemical treatment
and water-rinsing and also for the performance of two or more kinds
of chemical treatments and water-rinsing.
The present invention will be understood more readily by reference
to the following Example concerned with the application of the
apparatus as shown in FIGS. 1 and 2 to treatment of automobile
bodies.
Sixty automobile bodies each having a surface of 40 m.sup.2 were
subjected to degreasing, water-rinsing, phosphating, water-rinsing
and acidulating. For each water-rinsing, three zones were provided.
By the adoption of such water-rinsing in a three stage system, a
sufficient effect of water-rinsing was attained by using fresh
water supplied at a rate of 500 to 1000 liters per hour. (When a
conventional apparatus wherein each water-rinsing is effected in a
single stage is adopted, the supply of fresh water at a rate of
20000 to 30000 liters per hour is required to attain a satisfactory
water-rinsing.)
When a necessary amount of fresh water to be supplied is set at
2000 liters per hour, this corresponds to the increase of the
chemical solution in the tank. Thus, a fan may be so designed to be
capable of evacuating this amount of water in a vaporized state. In
the case of the temperature of the chemical solution being
60.degree.C, the evaporation of water is understood to be 0.12
kg.water/kg.air (dry) from FIGS. 4 and 5. Accordingly, the amount
of evacuation can be calculated as follows:
2000/0.12 = 17000 kg.air (dry)/hour
This evacuation amount can be easily realized with a conventional
fan available on the market.
Still, the various means contained in the apparatus of this
invention may be wholly or partly automationed by a per se
conventional manner.
* * * * *